1. Field of the Invention
Embodiments of the invention relate to a tape substrate and a semiconductor device using the tape substrate.
This application claims priority to Korean Patent Application No. 2005-74257 filed on Aug. 12, 2005, the subject matter of which is hereby incorporated by reference.
2. Description of the Related Art
Recent developments in the flat panel display industry, such as those related to liquid crystal displays (LCDs) and plasma display panels (PDPs) as well as related developments in thin film transistor (TFT) technologies, have resulted in dramatic changes to the nature and composition of tape packages generally used in a flat panel displays.
Conventional tape packages come in many different shapes and sizes and are implemented using a range of technologies. The tape carrier package (TCP) is one common type of tape package, and comprises a semiconductor package formed on a tape substrate having a window formed therein and a semiconductor chip mounted on the tape substrate using one of several available inner lead bonding techniques. Chip on film (COF) is another common type of tape package. The COF package generally comprises a tape substrate without a window and a semiconductor chip mounted on the tape substrate using, for example, a flip chip bonding technique.
The tape package generally comprises input/output wiring patterns formed on the tape substrate. These wiring patterns are used as external connection terminals. In some applications, the input/output wiring patterns may be attached directly to a printed circuit board or a display panel.
Figure (FIG.) 1 is a plan view of a conventional tape package 50. FIG. 2 is a related cross-sectional view of a flat panel display 100 incorporating tape package 50 of FIG. 1.
As shown in FIG. 1, exemplary tape package 50 is a COF package and comprises a tape substrate 10, a semiconductor chip 20 having multiple electrode bumps 22, and an encapsulant 30. Semiconductor chip 20 may be flip-chip bonded to tape substrate 10 using electrode bumps 22. Encapsulant 30 is typically used to protect a flip-chip bonded portion between tape substrate 10 and semiconductor chip 20.
Tape substrate 10 may include a base film 12 having an upper surface 11. Wiring patterns 15 are provided on upper surface 11. Upper surface 11 may further provide a chip mounting area on which semiconductor chip 20 is mounted. Sprocket holes 13 are arranged along the opposite edges of base film 12. Wiring patterns 15 are variously connected to electrode bumps 22 of semiconductor chip 20. Wiring patterns 15 generally include input wiring patterns 16 and output wiring patterns 17. Input wiring patterns 16 extend from one side of base film 12 to the chip mounting area, and output wiring patterns 17 extend from the opposite side of base film 12 to the chip mounting area. Input wiring patterns 16 and output wiring patterns 17 may extend in parallel rows from sprocket holes 13. A protective layer 18 may be provided on wiring patterns 15, exposing respective ends of input wiring patterns 16 and output wiring patterns 17.
As shown in FIG. 2, flat panel display 100 may include tape package 50, a panel 60 having a chamfered edge 66, and a printed circuit board 70. An anisotropic conductive film (ACF) 80 may connect tape package 50 to panel 60 and printed circuit board 70. For example, one end of output wiring pattern 17 may be connected to electrode bump 22 of semiconductor chip 20, and the other end of output wiring pattern 17 may be connected to the edge of panel 60. One end of input wiring pattern 16 may be connected to electrode bump 22 of semiconductor chip 20 and the other end of input wiring pattern 16 may be connected to the edge of printed circuit board 70. Flexible tape package 50 may be bent so that printed circuit board 70 may be located behind panel 60.
Accordingly, tape package 50 may have a bent portion 40. The portion of output wiring patterns 17 at bent portion 40 may be bent and input wiring patterns 16 may be located behind panel 60. The bent portion 40 of tape package 50 may be positioned quite closely around chamfered edge 66 of panel 60.
However, if tape substrate 10 is bent excessively, it may break at the bent portion 40 corresponding to the chamfered edge 66 of panel 60. Thereby output wiring patterns 17 may be damaged.
That is, output wiring patterns 17 may include a portion 17a exposed through protective layer 18 and ACF 80. The exposed portion 17a may thus be impacted by mechanical stresses generated during a bending process, thereby resulting in damage to output wiring patterns 17.
Unfortunately, during the manufacture of flat panel display 100, mechanical stresses are generated by the handling of panel 60. For example, during the assembly of panel 60 within its constituent chassis, mechanical stress is routinely applied to bent portion 40. These mechanical stresses may cause the exposed portion 17a of output wiring patterns 17 to crack, which may result in short circuits during a reliability testing, or worse still during customer use.